Clashes broke out early Friday between Israeli police and Palestinians at the Al-Aqsa Mosque, a major holy site in Jerusalem, and medics said at least 59 Palestinians were wounded.
It was not immediately clear what sparked the violence. The Islamic endowment that administers the site said Israeli police entered in force before dawn, as thousands of worshippers were gathered at the mosque for early morning prayers.
Videos circulating online showed Palestinians hurling rocks and police firing tear gas and stun grenades. Others showed worshippers barricading themselves inside the mosque itself amid what appeared to be clouds of tear gas.
The Palestinian Red Crescent emergency service said it evacuated 59 wounded people to hospitals. The endowment said one of the guards at the site was shot in the eye with a rubber bullet.
There was no immediate comment from Israeli authorities.
The mosque is the third holiest site in Islam. It is built on a hilltop that is the most sacred site for Jews, who refer to it as the Temple Mount. It has been a major flashpoint for Israeli-Palestinian violence for decades.
Tensions have soared in recent weeks following a series of attacks by Palestinians that killed 14 people inside Israel. Israel has carried out a wave of arrests and military operations in the occupied West Bank, setting off clashes in which several Palestinians have been killed.
Tens of thousands of Palestinians were expected to gather at Al-Aqsa for Friday prayers, as Muslims observe the holy month of Ramadan.
Weeks of protests and clashes in Jerusalem during Ramadan last year eventually ignited an 11-day war with the Islamic militant group Hamas, which rules the Gaza Strip.
Israel had lifted restrictions and taken other steps to try and calm tensions ahead of Ramadan, which this year coincides with the Jewish Passover holiday and Christian holy week, brining thousands of pilgrims and other visitors to Jerusalem.
But the attacks and the military raids have caused another wave of unrest.
Earlier this week, Hamas and other militant groups in Gaza had called on Palestinians to camp out at the Al-Aqsa mosque over the weekend. Palestinians have long feared that Israel plans to take over the site or partition it.
Israeli authorities say they are committed to maintaining the status quo, but in recent years nationalist and religious Jews have visited the site in large numbers with police escorts.
Israel captured east Jerusalem, home to Al-Aqsa and other major holy sites, in the 1967 war and annexed it in a move not recognized internationally. Palestinians want the eastern part of the city to be the capital of a future independent state including the West Bank and Gaza, which Israel also captured during the war nearly 55 years ago.